Process of preparing nitrohydroxyhydrocarbons from hydrocarbons



C. ELLIS Feb. 24, 1942.

PROCESS OF PREPARING NITROHYDROXYHYDROCARBONS FROM HYDROCARBONS Filed May 11, 1940 Jkm.

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(ffw/ am M www Patented Feb. 24, 1942 PROCESS PREPARING NITROHYDROXY- HYDROCARBONS FROM HYDROCABBONS Carleton Ellis, Montclair, N. .1., assignor to Standard Oil Development Co Delaware mpany, a corporation of Application May 11, 1940, Serial No. 334,643

'2 Claims. (Cl. 260635 This invention relates to a method of securing nitrohydroxyhydrocarbons from hydrocarbon raw materials. Further, it relates to a method of securing nitrohydroxyhydrocarbons by a joint aldehydation-nitration of hydrocarbon raw mav terial, followed byA combining the products of the aldehydation-nitration operation. Still furthere, this invention relates to the controlling of aldehydation and nitration reactions by making thesev reactions mutually interdependent. Further objects will be apparent from the following disclosure of my invention.

It has been known that hydrocarbons, particularly those of aliphatic nature, can be oxidized to furnish oxidation products such as aldehydes, ketones, acids, oxyacids and the like. However, one of the chief diiculties which has been associated .with such reactions has been that of controlling the reaction to produce a desired product. The reason for this is that the oxidation reaction,V once begun, is exothermic in nature,

I `V,and the heat developed by the reaction causes oxidation to proceed-'so rapidly that often the product of the reaction consists for the most part of coke, tar, and gases such as carbon monoxide and carbon dioxide. Various methods have been proposed to assist in controlling such reactions, as for example, by employing an inert diluent in the reaction mixturefor byv quenching the reaction by suddenly reducing the temperature of the mixture of hydrocarbon, oxidizing agent and diluent. However, these methods are often is end'othermic in character, that is, it requires the continuous application of heat to make the reaction occur to any extent. I have found that when a process in which treatment of hydrocarbons with nitric acid or other nitrating agent is conducted in the same reaction zone and is contiguous with a process in which hydrocarbons are treated with an oxygen-containing gas the two processesbecome mutually interdependent. That is, the endothermic nitration reaction serves to control the exothermic aldehydation or oxiday tion reaction. Further,v the'exothermic oxidation reaction'causes the nitration reaction to occur,

by furnishing the heat required by the nitration reaction.

The products from the controlled, joint aide-- hydation-nitration step are further interacted, according to my invention, to furnshnitrohydroxyhydrocarbons. Thus, I `am able to effect the production of nitrohydroxyhydrocarbons from a single raw material in a simple, one-stage, controlled process.

The accompanying drawing is a diagrammatic representation of one method of carrying out my invention and is merely illustrativein character. In the drawing, I is a pipe leading from a'source of hydrocarbon supply and 2 is a pump suitable for delivering liquids orgases under pressure. From pump 2 the material is conducted by pipe 3 to heat exchanger 4. From heat exchanger 4, the material which has entered through pipe 3 is led through pipe 5 to distributing valve 6. Pipe 1 conductsa portion of the material from distributing valve 6 to mixing valve I3.

Pipe 8 leads from a convenient source oi oxygen (not shown) while pump 9 is a pump suitable for delivering vapors under pressure. Pipe I0 leads from pump 9 to heat exchanger Il.

From the latter, pipe I2 conducts the materials difficult to put into operation,. and very often which have-entered heat exchanger II by pipe I0 to mixing valve I3. The materials which have entered mixing valve I3 from pipes 1 and I2 pass through reaction chamber I4. Reaction .chamber lI4 is placed in a container I5. The

latter also contains a suitable heating medium I6,`heated by any convenient means. The mate,- rials which have passed through reaction chamber I4 are conducted through pressure relief valve I1vand pipe I8 to coil I9, which passes through heat exchanger II., From coil I9 the treated materials are conducted through pipe 20 to reaction chamber 2l. Pipe 22 serves to conduct a portion of the hydrocarbon material from distributing valve 6 to mixing valve23. `Pipe 24 l leads froma convenient source of nitric acid (not shown) to pump 25. From the latter, pipe l 26 leads the material to mixing valve 23. From mixing valve 23, the materials are led through reaction chamber 21, which is immersed in heating bath I6 contained in tank I5. Chamber 21 pressure reliefvalve 28. From the latter, pipe A 5I serves to conduct the materials to coil '29,

is adjacent to reaction chamber I4, jand thematerials pass through reaction chamber 21 in a direction opposite to that taken by the materials iowing through reaction chamber I4. From reaction chamber 21, the materials pass through tities of hy terial. From chamber' 31, the wash material is led through valve 38, and pipe 39 into chamber 10 36. Thetreated material in chamber 36 may be withdrawn through valve 40 and pipe 40 to still 42. From still 42 a pipe 43 leads to coil 44 immersed .in condenser 45. The latter is equipped outlet 41 for cooling material. From coil 44, a pipe 48 leads to receiver 49. A rotary sliding vane pump 501s attached to ipe 48, so that the still may be operated under r duced pressure. if desired.

In operation a hydrocarbon material, which may be a pure hydrocarbon material, such as butane,- pentane, ethane or propane, or a mixture of hydrocarbon materials such as natural or point the entering hydrocarbon material is pre- 30 heated by the reaction products in coil 29 which flows through heat exchanger 4. The heated hydrocarbon material then passes through pipe 5 to distributing valve 6, and at valve 6, the hydrocarbon material is proportionately delivered, at a 35 predetermine rate, to pipes 1 and 22. The quanocarbon material which are delivered to pipes 1 and 22, will depend upon what final product is desired. For example, if it is desired to secure as end product, a compound or series of compounds which contain one nitro group and two hydroxyl groups per molecule, then distributing valve 6 is regulated so that out of every 3 volumes of hydrocarbon material entering valve 6, two volumes leave through pipe 1 and 1 volume through pipe 22. On the other hand, if it is desired to secure as end product a compound or series of compounds containing one nitro group and one hydroxyl group per molecule, then distributing valve 6 is fixed so that the hydrocarbon 5 material -which enters distributing valve 6 is divided-equally. In this manner, out of every two volumes of hydrocarbon material that enter` distributing valve 6 through pipe 5, one volume leaves through pipe 1 and one volume through pipe 22.

The heatedn hydrocarbon material which is con. ducted from distributing valve 6 through pipe '1^ is led to mixing valve I3, where it is admixed with a predetermined quantity of oxygen-containing gas. The latter is led from a convenient source of oxygen, such as air or compressed oxygen, to pump 3. Pump 3 serves to deliver a predetermined amount of oxygen-containing gas, at a definite pressure through pipe I0 to heat exchanger I, where\the oxygen-containing gas is preheated by the reaction products which flow from pipe I8 through coil I9 in heat exchanger I I. The preheated oxygen-containing gas passes from heat exchanger II through pipe I2 to mixing valve I3, where the oxygen-containing gas is mixed with the hydrocarbon material which has entered mixing valve I3 from pipe 1 and distributor valve 6. The relativejproportions oihydrocarbon and oxygenhcontaining gas which are l g2 ,l 2,274,630

admixed may be varied by setting of mixing valve I3. The proportions of oxygen-containing gas and hydrocarbon material which are mixed in mixing valve I3 may be varied widely, that is,

from 1 to |00 parts or more of oxygen-containing gas to 1 part. of hydrocarbon material. Ordinarily, however, a good ratio of oxygen-containing gas to hydrocarbon material is about or The hydrocarbon material-oxygen containing gas mixture then is forced, preferably under superatmospheric pressure which may be of the order of 150 to 1500 pounds per square inch or more, though ordinarily a pressure of 300 to 400 With an inlet 45, fOr 20011118 mterial. and an 15 .pounds per square inchissufdcientto furnish the desired results, through reaction chamber I4. The latter is immersed in a suitable heat transfer medium I6, placed in container I5. The heattransfer medium is heated to about G-420 C.

20 The time of the reaction of the hydrocarbon material and the oxygen-containing gas in reaction chamber I4 should be relatively short, of the order of 0.1 to 5 seconds or more, though I have found that a contact time of 0.5 to 2 seconds is 25 satisfactory to favor aldehyde formation.

At the end of the contact period mentioned above, the reaction products are led through pressure relief valve I1, whereby the pressure of the mixture is reduced substantially to atmospheric. In this way further reaction is inhibited, since the decrease in pressure of the reaction products brings about a corresponding decrease in the temperature of the mixture. The reaction products then are led through pipe I8 to coil I9, which is contained in heat exchanger II. In this way ythe reaction products are further cooled by heat interchange with incoming oxygen-containing gas. The cooled reaction products then are led through pipe 20 to reaction chamber 2|.

That portion of the preheated hydrocarbon material which is conducted from distributing valve 6 through pipe 22, is led to mixing valve 23. In mixing valve 26 thev preheated hydrocarbon material is admixed with nitric acid or other nitrating agent. The nitric acid is conducted from a convenient source (not shown) through pipe 24 to pump 25. Pump 25 serves to deliver the nitric acid or other nitrating agent under ,i suitable pressure to pipe 26, from which the nitric 0" acid or nitrating agent is led to mixing valve 23.

The relative proportions of nitric acid or nitrating agent and preheated hydrocarbon materia! which are mixed in mixing valve 26 may be varied within wide limits. depending upon the starting materials and extent of nitration desired.

When using nitric acid as nitrating agent. or-

dinarily a ratio of hydrocarbon to nitrating agent of between 4 and 14 or more to 1 is suitable, through I have found .that a ratio of about 9 or 10 to 1 is quite satisfactory.

The mixture of preheated hydrocarbon matei `rial and nitric acid or other nitrating agent then is conducted through reaction chamber 21., which is placed in tank I5. The time of contact of the mixture in the reaction zone is about 0.1 to 2 seconds, through -I have found that a contact time of less than 1 second is suitable to secure substantially complete mononitration of the hydrocarbon material present.

n From reaction chamber 21, the rection products are conducted through pressure relief valve 28, whereby the pressureof the reaction mixture is reduced substantially toratmospheric. In this u. manner, further reaction is inhibited. The reaction products then are led -through Pipe 'I t0 Reaction chamber 2| contains a buffer solution which is adjusted to maintain' an alkaline condition in reaction chamber 2|. The buier solution is stored in a reservoir 3|, from which it may be introduced into reaction chamber 2| by means of valve 32 and pipe 33.

The buffer solutionserves to neutralize any acidic materials which enter reaction chamber 2| as reaction products from pipe 20 and pipe 30. In this way any acids which are present in the reaction products of the oxidation step, such as fatty acids, hydroxyacids or oxyacids, flor example, are neutralized. Also, any acidic materials froml the nitration step such as nitric acid or oxidation products, for example, are neutralized. The alkalinity of the buffer solution shouldl be sufficient to maintain the mixture ln reaction chamber 2| 4at a pH of 7.5-9.0, though I have found that a pH of 8.0-8.5 is quite satisfactory. In other words, any buier solution may be used which will maintain an alkaline condition in reaction chamber 2|.

Instead of using a buffer solution to maintain an alkaline condition in reaction -chamber 2|, I

have found that alkali solutions may be used to storage chamber 49. In cases x'vhere vit is desired to distill under reduced pressure, .rotary sliding vane pump 50, which is attached to pipe 48, may be used 'to reduce the pressure under which distillation occurs.

In some instances, where the nitrohydroxyhydrocarbons secured according to my invention f are solids at room temperature, it maybe desirequally well. For example the material in reservoir 3| may be an aqueous solution of an alkali such as sodium carbonate, potassium carbonate,l calcium hydroxide, sodium hydroxide, potassium hydroxide or the like. When alkali is used instead of a buffer, sullicient aqueous alkali solution such as those mentioned above is introduced from reservoir 3| to reaction chamber 2| by means of valve 32 and pipe 33 to bring the mixture in reaction chamber 2| to an alkaline condition.

Under the conditions described above, the aldehydic material secured by treatment of hydrocarbon material with an oxygen-containing gas according to my invention will interact with the ntrohydrocarbons obtained by treatment of the hydrocarbon material with nitric acid or other able to secure these products asresidues of 4'distillation. Any convenient, means may bey employed to remove such still residues and to separate the nitrohydroxyhydrocarbons. For example, extraction, fractional precipitation or fractional crystallization may be employed.

It will be seen from the foregoing, `which is illustrative. in character, that my invention comprises a' method of securing joint aldehydation and nitration of hydrocarbon material. Further, my invention comprises a method of preparing nitrohydroxyhydrocarbons by securing joint aldehydatlon and nitration of a hydrocarbon material, and combining the products of the joint nitration and aldehydation stepunder alkaline conditions.

As was mentioned before, one of the outstanding features of my invention lies in the fact that the aldehydation and nitration reactions are interdependent. As is wellknown, treatment of hydrocarbon material with an oxygen-containing gas is an exothermic reaction. That is, once the reaction of an oxygen-containing gas and a hydrocarbon material has been nitrated, the reaction gives oil heat.' For this reason, reactions .'terial and an oxygen-containing gas, that not nitrating agent to furnish nitrohydroxyhydrocarbons. This reaction, which occurs in reaction chamber 2|, maybe conducted simply by mixing the materials in this chamber.

After a suitable| period of agitation, which may vary from 30 minutes to 5 hours orV more, depending upon the type of aldehydic and nitrated material present, the aqueous phase is withdrawn from reaction chamber 2| through Avalve 34 and pipe 35 to tank 36. In tank 36, the aqueous mixture from reaction chamber 2| is neutralized by addition of suicient acid, which is contained in reservoir 31. From reservoir 31, the neutralizing acid is conducted to tank 36 by means of valve 38 and pipe 39.

When the mixture in tank 36 has been neutralized, it is withdrawn through valve 40 and conducted through pipe 4| to still 42. The material in still 42 then is distilled under atmospheric or subatmospheric pressure, as desired, to separate the nitrohydroxyhydrocarbons secured according to my invention. In the cases Where the nitrohydroxyhydrocarbons are liquid at room temled through pipe 48 only can the latter reaction, i. e., aldehydation, be controlled, but also that nitration of the hydrocarbon material can be effected simultaneously. In otherl words, nitration of one portion of the hydrocarbon material serves to control aldehydation of another portion of the hydrocarbon material. In this manner there isV se.- cured a mixture of ntrohydrocarbons and aldehydes which further interact, according to my invention, to furnish nitrohydroxyhydrocarbons.

Hydrocarbon materials suitable for use in my invention include pure hydrocarbons such as ethane, propane, butane, pentane or hexane as- `well as mixtures of hydrocarbons such as natural gas or casinghead gas, light gasoline fractions or the like. In other Words, any hydrocarbon material which contains a substantial proportion of saturated or parafflnic hydrocarbons may be used in my invention.

By oxygen-containing gas I mean any gas or mixture of gases which contain oxygenin a free or uncombined state. For example, pure oxygen, air, oxygen diluted with an inert substance such as nitrogen, carbon dioxide, steam or the like, or air diluted with an inert substance may be used in my invention.-

While in the foregoing description of one method of carrying out my invention the joint aldehydation-nitration reaction was effected under superatmospheric pressure, it is 'to be understood that my invention can be effected, if desired, under atmospheric or subatmospheric pressure. The feature of my invention is, as was mentioned previously, the joint interdereactions by heat exchange between materials undergoing said reactions, combining aldehyde and nitro-hydrocarbon products of said reactions and interacting said products in the presence of an alkali. 2. The process according to claim 1, in which the gaseous paraffin subjected to said reactions is in a. mixture of paramnic hydrocarbons having 2 to 5 carbon atoms per molecule.

CARLETON ELLIS. 

